Chronic wasting disease (CWD), an emergent, efficiently transmitted, fatal prion disease of cervids (deer, elk, moose), is now identified in 15 states, 2 Canadian provinces, and Korea. We have found that infectious prions capable of transmitting CWD are present in the saliva, blood, and urine of CWD-infected deer, potentially explaining the lateral transmission of the disease. The presence of CWD prions in saliva and blood confirms prion infectivity in biological fluids and provides realistic hope for antemortem detection via a more sensitive in vitro assay, which forms the basis for this application. Direct detection of the abnormal CWD prion protein (PrPRES/CWD) in body fluids or excreta of deer has not been possible using contemporary assay methodologies (i.e. immunohistochemistry, western blotting, ELISA). Here we propose to employ serial protein misfolding cyclic amplification (sPMCA) to amplify and detect PrPCWD in saliva, blood, urine, and feces of infected deer. Direct in vitro detection of PrPCWD would enable pre-symptomatic ante-mortem diagnosis, improve ecologic understanding of CWD, and potentially enable detection of prion carrier states and contamination in cervid products. Whether a non-cervid reservoir for CWD infection exists in nature remains unknown. Likewise, whether CWD represents a risk to human health is uncertain. To begin to assess the potential for trans-species transmission of CWD, we propose to use sPMCA as a surrogate to assess whether the normal prion protein from selected non-cervid species can be converted to the abnormal PrPCWD isoform after exposure to CWD prions. This information will be used to direct correlative in vivo inoculation and epidemiologic studies needed to assess the CWD species barrier, identify potential reservoir hosts in nature, and better estimate potential human or other species health risks posed by CWD. PUBLIC HEALTH RELEVANCE: Chronic wasting disease (CWD) is a rapidly spreading fatal prion disease of deer and elk, probably spread through saliva, and now present in 15 states. Whether CWD may represent a risk to human health analogous to mad cow disease is unknown. Proposed here is a new more powerful test to detect CWD prions in saliva, blood, and excretions of infected deer-something not possible with current technology yet vital to controlling the spread of CWD among deer and potentially other species.